DESCRIPTION: In the United States, HIV infection has become a chronic disease with increasing evidence for an accelerated aging phenotype. By 2015, over half of HIV-infected individuals will be 50 years old or older. Notably, chronic HIV infection is associated with persistent inflammation, fibrosis and increased risk for frailty - conditions associated with muscl aging. We propose that persistent inflammation in chronic HIV infection promotes accelerated muscle fibrosis, which is then predicted to accelerate functional impairment, leading to a premature aging phenotype. We suggest that chronic inflammation promotes an imbalance in muscle tissue remodeling resulting in an accelerated, and potentially subclinical muscle fibrosis that is likely to limit physical function in the long term as the HIV population ages. We will recrit a cohort of at risk HIV-infected adults on stable ART and demographically matched uninfected adults to evaluate the following three specific aims: 1. Determine whether inflammation is related to skeletal muscle fibrosis in adults on effective ART. 2. Determine whether skeletal muscle fibrosis is related to physical function. 3. Characterize potential synergy between the fibrotic TGF?1 pathway and inflammatory pathway, and characterize the novel inflammatory inhibitor JQ1, the inflammatory inhibitor Rosiglitazone, and the fibrotic inhibitor Losartan. If fibrosis is confirmed in this study and there is evidence of activated TGF?1 signaling, these patients could be treated with anti-fibrotic agents such as Losartan, a Food and Drug Administration-approved drug with potent anti-fibrotic properties in skeletal muscle.